In recent times, conveyor elements are being increasingly associated to industrial process functions. For example, the task can consist in maintaining certain temperature relationships or conveying the bulk material under protective gas and under light gas pressure. Presently, the square cross section drag chain conveyor is being installed in an operationally safe fashion, for example, for temperatures from 250.degree. C. and air pressures of up to 600 mm water column. It has, however, been shown that, with two or more outlets, for extreme installation conditions, known type closure contrivances are not completely satisfactory.
A difficulty with the mechanical transport of bulk materials is unsatisfactory ambient conditions, for example, temperature variations, moisture, and dust. Regarding extremely rough operations, the opinion is often expressed that the track switching operation for the flow of the bulk materials has to be carried out manually and be monitored. The operator can then assist when the switching operation and/or closure is jammed or otherwise interfered with, monitor functionally important parts such as seals and bearings, and remove collections of dirt in dead corners.
There are a known number of closure systems with refined mechanisms which, theoretically are said to guarantee ideal closure functions. In practice, however, there have been numerous contradicting experiences in which unforeseen influences and disturbances have occurred so that, ultimately, the specialist, particularly in cases of closures for drag chain conveyors, again desires the earlier, more simple closure slides.
Regarding slide operation, convincing arguments can be set forth for separation of the slide and sealing function. That is to say, if one dissociates actuation means of the two functions, carrying out of one or the other activity can be monitored or indicated.
Through carelessness, however, the actuation means for the sealing function is often forgotten, so that the more sophisticated embodiment can, in practice, be even less satisfactory than the more simple embodiment.